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2-1A Writing Equations. Algebra 1 Glencoe McGraw-Hill Linda Stamper. In Chapter 1 you translated phrases. Phrases are translated into mathematical expressions . Sentences are translated into equations or inequalities. 6 + n. Phrase. The sum of 6 and a number.
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2-1A Writing Equations Algebra 1 Glencoe McGraw-Hill Linda Stamper
In Chapter 1 you translated phrases. Phrasesare translated into mathematical expressions. Sentences are translated into equations or inequalities. 6 + n Phrase The sum of 6 and a number 6 + n = 15 The sum of 6 and a number is fifteen. Sentence Sentence Seven times a number is less than 50. 7n < 50 When choosing a variable for an unknown, it may be helpful to select a letter that relates to the unknown value (for example: let a represent age). Sentences must have a verb! Sentences must have a verb!
When you translate from English to math, you must first determine whether the given problem is an expression (phrase) or a sentence. How do you know the difference? A sentence will have a verb. Some verbal expressions that suggest the equal sign are: is is as much as is the same as is identical to 3 times a number is 36. = 3n 36 Identify the verb. Write the equal sign. Translate the expression to the left of the verb. Translate the expression to the right of the verb. The equal sign is like a brick wall – nothing crosses to the other side.
Translate each sentence into an equation. 21 decreased by a number is 7. = Twelve is the sum of nine and a number. = 15 less than a number is 56. = Five times the number a squared is three times the sum of b and c. 5a2 = 3 (b + c) The verb is where you write the equal sign. The equal sign is like a brick wall – nothing crosses to the other side.
Example 1Translate each sentence into an equation. a. Four times n is the difference of 30 and n. 4n=30 - n b. Nine increased by a number is five squared. 9 + n=52 c. Ten less than a number is fifty. n – 10 = 50 d. The sum of two and a number is 9. 2+n = 9 e. A number decreased by five is four squared plus six. n-5=42 + 6 f. The sum of a number and six, divided by three is eight.
Example 2Translate each sentence into an equation. a. Fifteen more than z times 6 is y times 2 minus eleven. 6z + 15=2y - 11 b. Seven increased by a number is 21. 7 + n=21 c. A number b divided by three is six less than c. d. Twenty-seven times k is h squared decreased by 9. 27k = h2 - 9 e. Nine times a number subtracted from 95 equals 37. 95 – 9n = 37 f. Two plus the quotient of a number and 8 is 16.
A formula is an algebraic equation that relates two or more quantities. Example 3Translate each sentence into a formula. a. The perimeter of a rectangle equals two times the length plus two times the width. = length width width 2l + 2w P = 2l + 2w P = length b. In a right triangle, the sum of the squares of the measures of the legs, a and b, is equal to the square of the hypotenuse c. (hypotenuse) (leg) c a a2+ b2 = c2 b (leg) c. The perimeter of a triangle is side a plus side b plus side c. P = a+ b + c
HOMEWORK 2-A2 Pages 74-76 #13-18,23-26,35-36,50-51,57-68.